1. Field of the Invention
The present invention relates to systems that generate signals for displaying graphic images and/or video images.
2. Description of the Related Art
Displays are part of many systems and are often used as instruments to provide graphical information to operators of the systems. The information displayed can, for example, represent the current status of a system or represent video, graphical and/or textual information that is used by an operator of the system to control and/or modify the operation of the system. In many applications, displays provide a plethora of textual information shown simultaneously at different locations on the displays. The observer would, in many such cases, typically consider several different items or pieces of textual information to properly determine the status of the system or to reach a conclusion about the particular matter being displayed. In yet other applications, displays may provide other graphical information simultaneously with the textual information to allow an observer or operator of the system to more quickly understand or reach a conclusion about the information being displayed. Displays are also used as a tool for various communication based systems such as personal computers, televisions receivers and security monitors where the displays receive signals from a remote or local (or both) signal source and provide the information to a user of the system. In some cases, the displays are providing graphical and/or video information where such information originate from different sources. Displays are implemented with various technologies to create display devices such as Cathode Ray Tube (CRT) monitors, Liquid Crystal Displays (LCD) and plasma displays.
One key application of displays is their use in monitoring, in real-time, various events and to provide a visual indication of such events in graphics form thus allowing an observer of such a display to make decisions based on the occurrence of one or more specific events in particular relationship to each other. An example of the use of displays to monitor events are the flight display systems used by aircraft pilots to operate and/or maneuver aircrafts during (1) take-off; (2) flight and (3) landing. One of the key instruments used by aircraft pilots is a display commonly referred to as a Primary Flight Display or PFD. The PFD provides graphical information regarding the status of the aircraft in flight. The PFD provides relatively little information when the aircraft is on the ground stationary or taxiing away from the landing strip after it has landed or taxiing toward the landing strip prior to take-off. When the aircraft is in flight, the PFD provides various information about the aircraft such as its roll (angle of wings relative to horizontal), heading, and the degree to which the nose of the aircraft is pointing upwards, downwards relative to the horizontal (commonly called xe2x80x9cpitchxe2x80x9d). The graphics depicted by the PFD are arranged in a standard format to allow a pilot to quickly locate a particular information by focusing in on the particular part of the display screen to which the information has been assigned.
Referring to FIG. 1 there is shown a standard graphic and textual information arrangement for a PFD. Note that textual information is included with other graphical information to allow the pilot of the aircraft to determine the status of various sensor readings being provided to the aircraft while in flight. The sensor readings are various types of information from different sources which are converted to graphical signals that can be shown on the PFD. The xe2x80x9cinverted Vxe2x80x9d shown at generally the center of the display represents the aircraft. The aircraft is shown in reference to the horizontal. Referring now to FIG. 2 there is shown an annotated version of the PFD shown in FIG. 1. Some of the information labeled in FIG. 2 are used by the pilot while the aircraft is in flight, taking off or landing. For example, the xe2x80x9cZero Roll Referencexe2x80x9d is used as a reference point for determining how much xe2x80x9crollxe2x80x9d the aircraft is experiencing during flight. The roll bug depicts how much the aircraft is deviating from a zero roll orientation. The roll is a measure of how much the aircraft is rotated about its longitudinal axis (i.e., the axis that is oriented lengthwise of the aircraft). Also, various speeds are provided to the aircraft which are used by the pilot during take-off. Some of the critical speeds are referred to as xe2x80x9cV-speeds.xe2x80x9d V-speed V1 represents the maximum speed during take-off at which the pilot must take the first action (e.g., apply brakes, reduce thrust, deploy speed brakes) to stop the airplane. V1 also means the minimum speed in the takeoff, following a failure of an engine, at which the pilot can continue the take-off and achieve the required height above the takeoff surface within the takeoff distance. VR represents the speed at which the pilot must act to cause the airplane to rotate or pitch upwards during takeoff. A glossary of the various terms used to describe the displayed information in FIG. 2 can be found in 14 CFR (Code of Federal Regulations) part 1, of Federal Aviation Regulations Handbook which is incorporated herein by reference.
A perusal of the various labels in FIG. 2 indicates that most, if not all, of the information being displayed by the PFD are applicable when the aircraft is in flight. Some of the information such as VR, V1 and VREF are extremely critical in the control of the aircraft during take-offs and landings. VREF is a critical speed used during approaches and landings. The aircraft""s specific location on the runway prior to and during take-off is important to know for the proper operation of the aircraft. For example, for take-offs, the aircraft should be traveling at a certain speed at a certain point on the runway for a proper and safe take-off. The specific point on the runway at which the aircraft is to have a certain speed, such as VR, is one type of information that is not provided by a standard PFD. Various other information that can be extremely useful to a pilot of an aircraft during takeoffs, landings and during flight either are not available to the pilot or are not provided by the PFD. These types of information can be easily displayed on the PFD, but at the risk of (1) adversely affecting the clarity of the standard information that is typically displayed on the PFD and (2) modifying the particular arrangement of the information to accommodate for the additional information being displayed. The clarity of the information being displayed is adversely affected because more information is being displayed in the same area and therefore an information clutter develops which makes it more difficult to read the display and distinguish between various pieces of information. The traditional arrangement of the information may have to be modified to a certain extent to allow for the additional information being displayed. A modification in the arrangement of the displayed information results in pilots having to be retrained so they can quickly locate certain types of information at certain critical times during landings, take-offs or even during flight. More generally, the additional information to be displayed visually affects the overall appearance of the display so that a defined standard display will not only lose its clarity of appearance but also lose the advantages gained in having such a standard design. What is therefore needed is a technique for displaying additional information on a display already depicting information arranged in a standard or well defined arrangement without adversely affecting the overall clarity of the standard arrangement and without modifying the standard arrangement.
The present invention provides a display generation system and method for generating at least one underlay image having an embedded safety pattern and causing such underlay image to be displayed simultaneously with an overlay image such that the underlay image is compatible with and complementary to the overlay image. The display generation system has access to image databases containing image information that are used to generate the underlay image. The display generation system also has access to one or more data sources providing image information that are used to generate the overlay image.
The display generation system comprises a display processing engine that processes the information from the data sources to create display signals for at least one overlay image. The display processing engine also processes information from the image databases to create display signals for at least one underlay image having an embedded safety pattern. The display generation system further comprises an image processor coupled to the display processing engine, an integrity monitor module coupled to the image processor and a display monitoring module coupled to the integrity monitor module. The display processing engine provides display signals for both the overlay image and the underlay image with embedded safety pattern to the image processor. The image processor formats and processes the display signals so that they cause images to appear when applied to a display device.
The formatted and processed display signals are applied to the integrity module which uses the embedded safety pattern to obtain an image processing result, i.e., determine whether any unacceptable anomalies exist when the two images are displayed simultaneously by a display device. The integrity module then applies its image processing result and the display signals to a display monitoring module which performs error detection processing to obtain an error detection result, i.e., determine whether the simultaneous display of overlay image and underlay image contains any graphical errors. The display monitoring module is coupled to the display processing engine and thus transfers the image processing result and the error detection result to the display processing device. The display processing device will stop generating display signals if either a graphical error or an unacceptable image anomaly was determined.
A display device coupled to the display generation system of the present invention is thus able to display the underlay image simultaneously with the overlay image where the overlay image is generated by a system other than the display generation system of the present invention and where such other system uses the same data sources as those used by the display generation system to generate the overlay image.